ABSTRACT Each year, approximately 25% of US teens and emerging adults sustain physical, psychological, or sexual abuse by dating partners. Many victims of dating violence (DV) experience a host of devastating consequences, including acute and chronic mental and physical health problems, suicidality, delinquency, risky sexual behavior, substance abuse, and academic/occupational failure. Moreover, perpetrators of teen DV are at increased risk for continuing intimate partner violence in adulthood, and victims are at risk for future victimization and perpetration. The vast majority of what we know about DV is derived from cross-sectional studies, with a paucity of short-term longitudinal studies or long-term longitudinal studies where DV was a secondary focus often assessed with single-item self-reported indicators. Moreover, existing long-term longitudinal studies were conducted on older generations of adolescents. Given the changing landscape of sexuality and intimate relationships, shifting norms in support of aggressive behaviors, and the advent of electronic/social media, a contemporary long-term longitudinal study on DV is critically needed. To address these questions and gaps in the literature, our research team (PI: Temple) completed an 8-wave/8-year longitudinal study of DV in a large sample of 1,042 ethnically and socioeconomically diverse adolescents. Participants were recruited and assessed as Freshman/Sophomore high school students (Mean age=15) in 2010, with follow-ups annually from 2011 through 2017 (from age 16 through age 22). We are proposing to follow our current sample for an additional 5 years and add current partners of participants for the final 4 years. When finished, we will have 13 years of rich DV data covering individuals from young adolescence through young adulthood?during a period characterized by identity development and the beginning of dating to one characterized by identity formation and the establishment of more permanent intimate relationships and life trajectories. Specific aims are to examine 1) the longitudinal association of different forms of DV and their association with later DV across multiple relationships; 2) the long-term impact of exposure to DV and other adverse events on adult mental, physical, and psychosocial health; 3) dyadic influences on risk for, and protection from, DV across time; and 4) differences in DV perpetration and victimization over time by sex, age, sexual orientation, and race/ethnicity, and in the ability of risk and protective factors to concurrently and prospectively predict DV and other adverse outcomes in each subgroup. This will be the longest study ever conducted with a primary focus on DV, and provides an unprecedented opportunity to examine trajectories, risk and protective factors, course, and consequences of a wide spectrum of abusive behaviors. The study will undoubtedly inform the development of critically needed DV prevention and treatment programs.